1. Field of the Invention
This invention relates to an electromagnetic-induction-type position determination apparatus or digitizer which can be effectively used for inputting or digitizing hand-written characters and graphic figures to electronic equipments such as computers.
2. Description of the Prior Art
Recently, there has been increasing demands for less expensive position determination apparatus which easily enable the inputs of hand-written characters and graphic figures, as intelligent terminals for computers.
The electromagnetic-induction-type position determination apparatus have been known as one type of the position determination apparatus. This type of apparatus are widely used because they have such advantages that, owing to the spatial coupling of a pickup means such as a writing pen and a cursor and an interface plate through spaces, tracing-inputting of manuscripts can be executed on the interface plate and they keep accurate operations and high reliability even if the surface of the interface plate is dirty.
Some of the conventional electromagnetic-induction-type position determination apparatus were introduced in the NIKKEI ELECTRONICS, issued on Oct. 2, 1978 pages 118 through 131. However, the conventional electro-magnetic-induction-type position determination apparatus require many fine conductive wires to be minutely installed on their input boards in order to obtain high resolution. Accordingly, they inherently have such disadvantages that handling a tremendously large quantity of outgoing lines is troublesome, and that wiring the conductors precisely is difficult. These disadvantages become more serious to the large size interface plates.
Although such position determination apparatus are available that has less number of outgoing lines by using coil-shaped conductors on their input boards without deteriorating their resolution in order to solve the above-mentioned disadvantages, they have other problems that their control circuits and detection circuits become more complicated and more expensive.